Lecture 23 Metabolism Metabolism is the set of
Lecture 23: Metabolism ﺍﻷﺽ Metabolism: is the set of chemical reactions that occur in living organisms to maintain life to grow and to reproduce. Metabolism is usually divided into two categories: a) Catabolism; ﻫﺪﻡ breaks down organic matter, for example to produce energy in cellular respiration (from large to small). b)Anabolism; ﺑﻨﺎﺀ constructing ﺗﻜﻮﻳﻦ / ﺑﻨﺎﺀ components of cells such as proteins and nucleic acids (from small to large). Enzymes are important to metabolism because they act as catalysts to allow chemical reactions to proceed quickly and efficiently.
Important biochemicals: 1 - Proteins: Proteins are made of amino acids arranged in a linear chain and joined together by peptide bonds. Many proteins are the enzymes that catalyze the chemical reactions in metabolism. Other proteins have structural ﺗﺮﻛﻴﺒﻴﺔ or mechanical ﻣﻴﻜﺎﻧﻴﻜﻴﺔ functions, such as the proteins that form the cytoskeleton. Proteins are also important in cell signalling ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺨﻠﻮﻳﺔ , immune responses ﺍﻹﺳﺘﺠﺎﺑﺎﺕ ﺍﻟﻤﻨﺎﻋﻴﺔ , active transport across membranes ﺍﻟﻨﻘﻞ ﺍﻟﻨﺸﻂ ﺧﻼﻝ ﺍﻷﻐﺸﻴﺔ.
2 - Lipids: Lipids composed of three fatty acids and glycerol molecule. They construct ﺗﻜ ﻥ part of the cell membrane. They are a source of energy. Steroids such as cholesterol are another major class of lipids that are made in cells.
3 - Carbohydrates: Carbohydrates are straight-chain with many hydroxyl groups that can exist as straight chains or rings. Carbohydrates are the most abundant ﺍﻷﻜﺜﺮ ﺗﻮﻓﺮﺍ biological molecules, and found as storage for producing energy (e. g. glycogen) and structural components (cellulose in plants, chitin in animals). The basic carbohydrate units are called monosaccharides and include galactose, fructose, and glucose. Monosaccharides can be linked together to form polysaccharides.
4 - Coenzymes ﻳﻨﺔ / ﺇﻧﺰﻳﻤﺎﺕ ﻣﺴﺎﻋﺪﺓ Metabolism involves chemical reactions, most involve metabolic intermediates ﻭﺳﻄﺎﺀ called coenzymes. One central coenzyme is adenosine triphosphate (ATP), the energy source of cells. and used to transfer chemical energy between different chemical reactions. ATP acts as a bridge between catabolism and anabolism, with catabolic reactions generating ATP and anabolic reactions consuming it.
5 - Vitamins: Vitamin is an organic compound needed in small quantities that cannot be made in the cells. In human nutrition, most vitamins function as coenzymes after modification. 6 - Minerals: They are inorganic elements play important roles in metabolism; (e. g. sodium and potassium). About 99% of mammals' mass ﻭﺯﻥ ﺍﻟﺠﺴﻢ are the elements carbon, nitrogen, calcium, sodium, chlorine, potassium, hydrogen, phosphorus and oxygen.
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